Open Access Conference Proceedings

<div>Aircraft fuselage shells made from aluminium are coated to withstand the external influences from aviation. The corrosion protection consists mainly of an anodic oxide layer as the interface (IF) and a primer as the coating. As the coating can be damaged during the forming process, Original Equipment Manufacturers (OEMs) such as Airbus restrict the process chain so that the coating may only be applied onto the finished formed part. Previous studies with regard to the evolution of coating properties during forming have shown that a particular incremental bending process known as Deharde Polygon Forming® (DPF®) shows the potential to overcome these limitations. Thus, it could be possible to apply coatings to flat sheets before forming. That could save energy as well as environmentally harmful alkalis and acids for anodizing. As the IF shows the highest hardness of the coating-interface-substrate (CIS) system combined with a small thickness, it can be assumed that the IF is more endangered to failure. This paper therefore presents the results of an analysis of the interface before and after forming. Scaled fuselage shells are incrementally bent by DPF® to induce process-related deformations. Specimens from the initial state and from scaled fuselage shells are investigated by scratch and indentation tests with a Triboindenter TI 950. Due to the low plastic deformations induced by incremental bending with DPF® neither Young’s modulus and hardness nor elastic and plastic behaviour undergo significant changes. Hence the obtained results imply opportunities for flexible adjustments to the process chain regarding forming and coating.</div>

Keywords: Incremental bending, fuselage shells, interface properties, coating, nanoindentation, scratch, SPM

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